1. Field of the Invention
The invention relates to a signal transmission cable structure and, more particularly, to a signal transmission cable formed in flat and flexible shape.
2. Description of the Related Art
A signal transmission cable is conventionally used to connect, for example, a telephone handset or different computer components.
FIG. 1 and FIG. 2 are respectively a perspective view and a cross-sectional view showing a conventional signal transmission cable. As shown, a conventional signal transmission cable 1a is usually cylindrical, and comprises an insulating body 10a, a woven fabric layer 11a, a tin foil 12a, a nylon thread 13a, a ground line 19a, an insulating layer 18a, two signal lines 14a, 15a and two power lines 16a, 17a. The insulating body 10a is made of PVC having good insulating properties, and is the outmost layer of the signal transmission cable 1a. The woven fabric layer 11a is placed within the insulating body 10a, and acts as anti-interference protection. The ground lines 19 and the tin foil 12a are placed within the insulating layer 10a. The ground lines 19a are placed between the tin foil 12a and the woven fabric layer 10a. Within the tin foil 10a is further arranged the nylon thread 13a to improve the flexibility of the signal transmission cable 1a. The two signal lines 14a, 15a and the two power lines 16a, 17a within the nylon thread 13a and the two signal lines 14a, 15a are together encapsulated within the insulating layer 18a to prevent interference. In application, a terminal end of the signal transmission cable 1a is connected to a signal plug 2a. 
Although the above conventional signal transmission cable has good signal transmission results, its outer shape however is cylindrical and occupies a substantial space when being wound. The conventional signal transmission cable cannot be therefore conveniently received in a device body and need an external receiving member. If the user carries outdoor the electronic device to which the conventional signal transmission cable is connected, the user further needs to take with him/her several additional connecting lines which connection is time-consuming. The additional connecting lines further take substantial occupation space and may be lost. If the signal transmission cable is outwardly laid on a flat surface, the resulting protrusion of the cable is not aesthetic and further may easily causes a walking person to stumble. Moreover, with a cylindrical outer shape, the different lines within the cable are separated with a relatively small spacing distance, which easily causes interference. Because bending of the cylindrical cable may further negatively affects the signal transmission, the nylon thread is therefore traditionally needed to increase the flexibility of the cable, which increases the fabrication cost.
It is therefore a principal object of the invention to provide a structure of signal transmission cable that is formed in a flat and flexible shape, which enables easy winding in a cable-receiving case, prevents interference between the different lines within the cable, does not protrude when laid on a flat surface, and reduces the occupation space when received within a device body.
It is another object of the invention to provide a structure of signal transmission cable which construction does not need a nylon thread to have a good flexibility, which reduces the manufacturing cost.
To accomplish the above and other objectives, a signal transmission cable of the invention, formed in a flat and flexible shape, comprises an insulating body as outmost layer of the signal transmission cable. A woven fabric layer is arranged within the insulating body. A tin foil is arranged within the woven fabric layer. Two signal lines are encapsulated within the tin foil, and two power lines are placed within the insulating body. The signal lines and the power lines respectively are covered with an insulating layer.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.